Servo unit test stand



1949- A. F. KOPISCHIANSKY 2,459,535

SERVO UNIT TEST STAND Filed May 14, 1945 3 Sheets-Sheet l I N V EN TOR. ANDREW /7' KOPISCHIANSKY ATTORNEY I 1949- A. F. KOPISCHIANSKY 2,459,535

SERVO UNIT TEST STAND Filed May 14, 1945 I 3 Sheets-Sheet 2 INVENTOR. BY ANDREW F KDPISOHIANSKY ATTORNEY 1949- A. F. KOPISCHIANSKY 2,459,535

SERVO UNIT TEST STAND Filed May 14, 1945 3 Sheets-Sheet 3 m IL E g IN V EN TOR.

ATTORNEY BYY'ANDREW E KOP/SCHIANSKY k 5, oww um Patented Jan. 18, 1949 NT OFFICE snnvo UNIT TESTSTAND M Andrew F. Kopischiansky, Maple Heights, Ohio, assignor, by mesne assignments, to l Jack & Heintz Precision Industries, Inc., Cleveland, Ohio, a corporation of Delaware l.

Application May 14, 1945; Serialf No. saasisffl 7 Claims. (Cl. 73"37)- This invention relates to a test stand for testing aircraft hydraulic servo units and the like.

In the manufacture of hydraulic servo units certain routine inspections and tests are necessary to check the precisionof manufacture in the operation of the completed unit and the object of the present invention is to provide a convenlent test stand for performing the necessary tests rapidly and accurately on the production line.

There are certain important requirements which must be satisfied before a servo unit is acceptable for use in aircraft. Each piston must be free to move throughoutits full stroke with a maximum pull or push of a designated number of pounds. With one end open to the atmosphere and the opposite end under oil pressure" the servo motor valves must be adjustable to sustain the operating pressures in both directions, and the valves must be capable of retaining their adjustments within certain pressure limits. No external leakage is permissible when the servo unit is subjected to a certain designated excess pressure except from the piston rod end glands where a leak: age of only a few drops per minute is permissible.

Permissible leakage around the piston must not exceed and preferably be less than a specified number of cubic centimeters per minute. Also,

the individual pistons must be capable of exerting the scale pull for which they are designed, at operating pressures.

The specific objects of the present invention are to provide a test stand for quickly and easily performing the various tests required to determine if a servo unit meets the above individual requirements.

These and other objects will be apparent to those skilled in the art as the specification proceedsin connection with the accompanying drawings illustrating the preferred embodiment in which,

Figure 1 is a front elevational view of the test stand,

Figure 2 is a piping diagram of the hydraulic system in the test stand and, v

Figure 3 is a schematic wiring diagram of the electrical system for operating the hydraulic system and performing other functions;

Referring first to Figure 1 the numeral 3| indicates a bench having a rear panel 32 and end panels 33 and 34 arranged in the manner shown. Centrally located on the bench 3| is a supporting jig 5 provided with meansto clamp a servo unit 6 thereon. The rear panel carries a large gage glass 1 and smaller gage glasses 8 to l3. Also at opposite endsof the rear panel are a liquid pressure 1 sage and a clockl5i j I The endpanels 33 and 34 are each providedwith a horizontal bar l6 for supporting spring scales I1 and IBimmediately above the pulley blocks [Sand 20. Each of these pulley blocks is provided with three upper pulleys 2i and'three iower pulleys 2 2 aligned with the respective pistonrodsofthe servo unit. Weights 23 are supported by cablesf24 passing over the lower pulleys 22 andprovided with connectors 25 adapted to make connection withthe individual servo motor piston rods'for measuring the pull thereof. When njotiri us the weights 23 may be supported inthe mariner shown by hooking the connectors '25 over suitable anchoring means in the lower part of the base 5. Oneor more cables 26 having connectors 25thereonjare providedfor attaching thefpiston rods to the scale 18 for measuringthe pull on the'piston rod."

As bestshown in FIgure ZjtheserVo unit 6 for which the present test stand is designed has three cylinders I, 2 and3fhaving three pistons which may be moved by hydraulic pressure eitherto the right or to the left. "I he'threepistons are con-1 nected with the, left hand piston rods35, and right hand piston rods 36 for actuation of thecontrol surfaces of an aircraft. The three cylinders have hydraulic lines3 l, 38 "and 39 communicatingwith the left endsthereof' and hydraulic lines 40, H and flfcomlnun icating with the right ends there: of. It is understood thatthesehydraulic lines are a'lternately pressure and reliefjlines when the servo unit is operating, dependingupon the di rection the pistonis moving. The above-men tioned hydraulic lines communicate with solenoid valve assemblies 43 to 48 *in. the manner shows; .A plurality of pipes 5!! connect the above-mentioned solenoid yalv'es with another series of solenoid valves 6 0to6 5,"eaeh of thelatter be'ingconnected with a pressLurle lineGG and a relief line 61. Hydraulic pressure is established in the pressure line by means of p mp 10 supplied from ,asur'np J I. Pressure regulatorsn and '13 associated with a push -pull valve 14 provide for establishing either a normal operating pressure or a hightest pressure in the system. ,Tliejrelief line 61 discharges through ayalve l5into thebottom of the tube 1. Tube 1 overflows through a pipe 16 into the sump. A large return line. 'lTalso discharges into the sump, this line bei ng open to atmospheric pressure at some high point 18 in the system. 'Ihe return or sump line I! ,connectswith a pipe 19 receiving the overflow from each of the gageglasees 8 to I3, and with; a pipe BO connected in turntoeachof the solenoid intestate 48, The gage glasses .8 to we e supplied by pipes 81 to 86 communicating with two ports in each of the solenoid valve assemblies 43 to 48.

Figure 3 discloses an electrical system for operating the various solenoid valve assemblie in the hydraulic systems to control hydraulic pressures in the system to perform the desired tests. The electrical system comprises ,a bank of switches for operating the servo pistons individually, right or left, means for resetting the clock, means for. moving the pistons simultaneously to'the right or to the left and connecting the relief lines with the ga e glasses for measuring leakage, and means to provide aut m i cycling to run in the servo unit under continuous operation for any desired time.

A 110 volt supply 90 is used tor the clock and intermittent contactor for cycling, and a 220 volt supply 9| is used for the solenoid and electromagnetic switch. The" intermittent contactor is indicated by the numerals I and comprises a small motor 9.3.:for continuously moving a switch arm 94 to produce periodic energization of .a icontactor 95 having an energizing winding 96 and .a movable contact element 9?! shown in midaposition. When the winding .96 is energized the .---contact element .91 vmoves to the right in the direction of the arrow :to complete circuits through lines 98 -.and 39. When the winding 96 is not energized the comtactelement 91rests in its opposite position completing a circuit through line vIllll, the movable contact element itself beingconnected with one side of the supply 9|.

The numeral 101 designates a plural circuit contactor having an energizing winding N12 for moving on armature carrying the contacts J03 and IL, 2L, 3L, IR, .2R,.and 3R to ,theright asindicated by the arrow, to complete :circuits through lines 99 I110, In], and I115. When the Winding ll 02 is not energized the movable armature returns the movable contacts {into engagement with an opposite set of stationary contacts for energizing lines M to H5 connected with three double-pole double-throw switches 56, M11, and H8. The numeral 120 indicates apush-button switch for starting and stopping the Pump which is designed to run continuously.

.Switches IZI to 12.3 are similar to the switches I I6 to H8 but have only certain .of their contacts wired into active circuits. The switch I2I com pletes acircuit from the wire 1.05 "leading to the H11 Volt supply, through a line 1.01 to the reset winding I24 of the clock 15,. A line wire l25f-rom the 110 will: supply 991s connected with the intermittent contactor motor v2'43 and withrthe res t, motor, and clutch windings of the clock, the latter being designated'by thenume'ralsJZ-B and I21. The clock motor-circuit is completed through line I05; and the clutch .-circuit is completed through line I04 which is connected with the swittihesllli to, H8 for energizatlon in all positions of these switches and connected with a stationary contact eaigageable by one of contacts 103 in contactor The "220 volt supply 9| is connected through a line I which branches into the twulines 1.34 and I32 to connect with the solenoid coils and the contactor windings 96 and I112. The circuits of solenoid valve assemblies 43 to -48 are completed through wires I33 and .134 leading to the opposite sides of switch I22 and thence .tothe other side of the line I'35. The circuits for thesolenoid valve assemblies 60 to '65 lead to the movable contact elements IL, 2L, 9L, 2E, and 3R to be completed through the lines I'Ill to I I5 when the contactor {coil 1112 is fie-energized and 4 through to the lines 99 and I08 when this contactor is energized. The lines H0 to H5 are adapted to be selectively connected with the line Wire I35 in the difierent positions of switches I16 to H8, and one or the other of the lines 99 and MB is connected with the .220 volt supply at the line I35 by the movable lcontactlll'l in contactor 95.

The individual operation of the servo pistons will first be described, whereby the piston may be allowed to travel freely to the end Of its stroke :ormay be, connected with a cable 26 to register the pull-on the scale It. Assuming both con- 1tactorsi95 and Hi?! to be de-energized, the closing of'the switch '6 to the position designated IR will .be seen to complete a circuit from the line 135 through the wire I I0 and movable contact IR on the large oontactor IllI to solenoid valve assembly 63 and returning through wires I32 and I39. Energiaation of the solenoid valve assembly 53 lifts the valve piston and thereby admitspressure from, the pressure line to pipe 59 and thence through the de-energized solenoid valve assembly '45 througnpipe 49 to the right side of the cylinder I to move its piston to the left. When the piston thus moves to the left, theleft end of the cylinder is connected through pipes 31 and 59, and de-energized solenoid valves 43 and fill, with the relief line .63, When the switch I16 is thrown to its lL position a similar circuit iscompleted from wire I35 through movable .contact .=I L on the contactor .l0,I to energize solenoidvalve assembly .Ell to admit fluid pressure through thelines 66, 59 andiil .in asimilar manner to the left .e 'of cylinder 1 to move the piston to the right. When the piston is moved to the right, the right end of the cylinder is connected through pipes All and 59 and die-energized solenoid valves 46 and .63, with relief line 61. Whichever the switch is moved a circuit is completed through wire lild to engage the clutch of the clock for "a timing interval. After each operation the clock may'he reset byvmomentaril closingfswitoh 121,, Theswitches ill and 51B operate in a similar manner to produce individual left and rig'ht movements of the pistons 1n the .cyl1intiers? and 3 under manual control, the electrical and hydraulic circuits for these cylinders Lcor.

- responding to the circuits lust describedfor cylinder-1.. I

y The switch I 22 .is vefiective to move all thepistons either to 'the'rlght or to the left andlto conmeet the relief ends of the vcylinders to the appropria'te gage glasses tovi-sually indicate the leakage .in a particular time interval. Thus, if switch I22 is moved to its upper position a circuit will be completed from line 3.35 of the 220 volt supply throughline 1'33 and solenoid valve assemblies 43 to 45 so as to connect the gage glasses 8, ,SQ-"Ill through their pipes 3 I, 82, 33 with the left ends of the cylinders I, 2, 3' respectively, and to cut oil" these gage glasses from the sump lineSD to which they are normally connected when the solenoid valves 43 to 45 are de-energized. This'position of the switch. e150 completes a circuit from wire [35 through wire hill to energize contact-or coil I02 throughreturn wires 1.32 and I30 to move the armature'thereof to the rights This position of the armature establishes circuits through solenoid valve assemblies '63 to 65, these circuits being completed through line 1110 through the contactor which die-energized. .Energization of solenoid valve assemblies 6.3 to 55 connects the pressure IineIi-fi with the three servo motor lines 40 to 42 to the de-energized solenoid valves 46 guesses to 48 to move the -servo pistons to the left. "Any hydraulic fluid leaking pasttheby-pass-orpast the pistons in'the servo unit will then appear in thegage'glasses "8, 9,and I When the switch I22 ismoved to its opposlteor lower position the solenoid valves 46 to "will be energized by wire I34 to connect the gageglasses II to I3 with the right ends of the servo cylinders. The contactor winding 96 will also beenergized through wires III and I3I to operate that contactor to energize the winding I02 of the contactor IOI through wires I30, I32, and"'98. I Actuation of both contactors 95 and IOI in thismanner will be seen to complete circuits through the movable contact elements IL, 2L, and3L to energize solenold valve assemblies 60 to 62. Thiswill establish hydraulic connections similar to those previously described in this case connecting the, pressure line 66 with the servo unitlines 31to 39 to move the three pistons to theright. ,Internalleakage. will appear in the gage glasses II to I3. 1 r

The switch I23 has only one on? position and its purpose is to'produce automatic cycling of the servo pistons back and forth under the control of the intermittent contactor 92. Closing of this switch establishes a circuit through one pole from wire I35 through wires I40, I32, and I to energize the contactor IOI, moving all themov'able contact elements to the right in the direction of the arrow. Thus, the contact elements I03.keep 110 volt circuits through theintermittent' contactor motor 93 and the clocklclutch I21. The other pOleof switch I23 completes a circuit from wire I through wire I42 'and the intermittent contactor to intermittently energize contactor 95 through return wires I3I and I 30. The intermittent contactor is designed to produce on and oif intervals of approximately equal duration so that the movable contact element 91 in the conductor 85 will establish circuits in the lines 99 and I00 alternately and of substantially equal duration. The line 99 energizes the solenoid valves 60 to 82 to admit fluid under pressure to the left ends of the cylinders to move the three servo pistons in unison to the right, and the line I00 energizes the solenoid valve assemblies 63 to 65 to admit pressure fluid to the right ends of the cylinders to move the servo pistons to the left, the frequency of reciprocation being that of the intermittent contactor 92.

Thus, the above described switching arrangements provide for applying hydraulic pressure to opposite ends of the servo cylinders individually to test the pulling power of the pistons in opposite directions and to measure the leakage from the individual cylinders. The pistons may also be moved to opposite ends of the cylinders simultaneously by a single switch manipulation and by another switch they may be set in continuous reciprocation for any desired length of time under the control of automatic cycling mechanism. Each of these tests may be timed by an electric clock having a magnetic clutch to initiate a timing interval coincidentally with the actuation of the solenoid valves involved in the particular test.

Various changes may be made in the construction and arrangement of parts, and in the electric and hydraulic circuits, within the spirit of the invention, and all such modifications within the scope of the appended claims are included in the invention.

I claim:

1. In a test stand for multiple cylinder and piston servo units, a system of hydraulic lines adapted to be connected to opposite ends of said servo unit cylindersto operate the pistons therein, a hydraulic" pressure line, a hydraulic relief line, a plurality of solenoid valves for selectively connecting said pressure and relief lines with different-ones of said hydraulic lines to operate said servo unit in a particular manner, an electrical control system having switch means for selectively energizing said solenoids to proof a servo unit to be tested, hydraulic pressure and relief lines, a plurality of calibrated gage glasses equal to the number of cylinder endsin the servo unit to be tested, a first plurality of solenoid:valves for connecting said pressure and relief lines with said hydraulic lines so as to admit pressure in predetermined ends 01 the servo unit cylinders and to. connect the low pressure cylinder end-s to the relief lines, and a second set of solenoid valves operable toconnect said gage glasseswith the'low pressure endsof the servo unit cylinders and to disconnect the relief lines therefrom to measure internal leakage in each of said servo unit cylinders individually.

3. In a test stand for. multiple cylinder and piston servo units, a plurality of hydraulic lines adapted to be connected with opposite cylinder ends of a servo unit to be tested, hydraulic pressure and relief lines, a plurality of liquid gage glasses corresponding to the number of cylinder ends in said servo unit,a first series of solenoid valves arranged to connect said relief line and disconnect said pressure line from said servo unit when said valves are de-energized and to disconnect said relief line and connect said pressure line to respective hydraulic lines connected with said servo unit when energized, a second set of solenoid valves connected with said first set of solenoid valves so as to establish communication between said cylinder ends and said first solenoid valves and to connect said gage glasses with another relief line when de-energized and when energized to disconnect said pressure lines from said servo unit and to connect said gage glasses with respective low pressure ends of cylinders in said servo unit.

4. In a multiple cylinder and piston hydraulic servo unit test stand a plurality of hydraulic lines adapted to be connected to the operating connections of said servo unit, at opposite cylinder ends pressure and relief lines, a plurality of liquid gage glasses corresponding to the number of cylinder ends in said servo unit, a first series of solenoid valves there being one valve corresponding to each cylinder end in the servo unit, a

second set of solenoid valves, each valve beingv connected to one cylinder end in said servo unit and to one of the solenoid valves in the first set. pressure and relief line connections with said valves in said first set, and connections between each valve of said second set and its corresponding liquid gage glass, said hydraulic connections and valves being arranged so that when the valves of said first set are de-energized they open relief lines and clese .pressurelines to said-servo unit and when energized they close relief lines and open pressure .lines in .said servo innit ;the valves of the second set establishing communication between said servo unit and the valves 0f thexflrst set andnconneetingmhe liquid gage-glasses witna separate relief line when ;de energized,-,and disconnecting said relief line :fromsaid a e glasses and eonneetinglines from thetgaeegglasses to-t'he servo unit when energized.

'5. A servo unit {nest stand comprising .a pinrality; of :solenoid valves-I01 lcontrollingspressure and relief lines :to opposite ends, of individual cylinders 'in the servo unit, :a cl-ockhaving. reset andeclutch circuits, a plurality of switchesqfer energizing individual snlenoids to admit thy draulic pressure to 'apredetermined sylinder-en-d, said switches also inculclin means izfnr closing said wclutch circuit to start. ;a timing ioperation coincident with the admission of :hydraulic ;pr.essue to the servo unit and .a switch ion-closing saidmeset vci neuit to mesetsaid elock.

Acmultiple =icy1i-nder and piston hydraulic serve *unit test stand cempris'ing solenoid valves laor eonneetingfithe servo unit i-to he mes-ted with a hydraulic :.pressure and relief lines, :a liquid gage glass =f0r each cylinder end theseixvo'unit to be tested, additional 'rselen oid valves intercom inectedneleotrically wand hydraulically with said first-solenoid valves for connecting. individual ends of :cyli nderslin said servo unit withsaidliq- :uidigage glasses: individually, electrical: operating circuit for said solenoid valves, 1 andswiteh, means for can-trolling said cincuits to pr-educeigperatlon of the sen/.0 unit pistons insither direction-and for connecting pressure lines to certain end of :therservo unit cylinders:and eaeeiglasses meson- Q 'posite .enzd mi she .eylinders -:-t0 measure {internal leakage inmherservozunit.

7,,iAwmulti-pleey1inderandmistenservo unit test stand comprising a iirst'zsetiefsolenoid valves, ne rim seaeh cylinder iend .z'Qf said. serve unit and each valve connected to 10ne-pf,-=sai-d syliinden-ends, a; series at :gage glasses,,- one -f-oi' eeanh cylinder lend andmeaieh gage glass. ,being icon- ,BQCtBd LSOAW :ef :said. valves, a relief lineeomineeted itmeach 41f said Halves .tn-drain: said gage lasses,- aisecondrseh-nf; selenoid valves, eaehwalve efsa-idiseeond set connected ta ,oneyvalveiof said first, set, ands-pressure and i'eliet iiinesr rmn- ,neeted. with ithe valves of said zsecondirset and "UNITED STATES PATENTS fbl-imiher 

